Where is this code coming from? Can you provide information on how you’re using this code? If you’re able to reproduce this problem in a new project, please also include the reproduction steps to help me test the issue locally.
I took this code from “4.xx\Engine\Shaders\ShadingModels.usf”. To reproduce bug you have to create a material with hair shading type. This material have output called “backlit”, but this output makes no effect on the rendered image.
I have tested a bit this issue:
There is a render with default hair shader (backlit hardcoded to 1)
There is a render when I changed backlit value to 0 directly in the shader file
But when I trying to set backlit value in the material nothing changes
What are you trying to achieve? If you are trying to get better results with your characters hair you should be able to leave the backlighting value at 1 in the code.
I would recommend using the same material setup for the hair that is provided in the content examples. Once you have tried this let me know how the results turn out and I will continue to help you get the look that you want.
Now it looks better, but I played with backlit in the content example hairs and it still seems broken - nothing changes when I change backlit from -1.0 to 1.0 and even -1000.0 to 1000.0
I’ve filled a bug report that is related to this post. I also added what you mentioned in a private comment to the devs. The only thing that seems to influence back lighting is the dynamic shadow distance on a directional light.